# uncompyle6 version 3.2.3
# Python bytecode 3.6 (3379)
# Decompiled from: Python 3.6.8 |Anaconda custom (64-bit)| (default, Feb 21 2019, 18:30:04) [MSC v.1916 64 bit (AMD64)]
# Embedded file name: site-packages\dateutil\easter.py
"""
This module offers a generic easter computing method for any given year, using
Western, Orthodox or Julian algorithms.
"""
import datetime

__all__ = ["easter", "EASTER_JULIAN", "EASTER_ORTHODOX", "EASTER_WESTERN"]
EASTER_JULIAN = 1
EASTER_ORTHODOX = 2
EASTER_WESTERN = 3


def easter(year, method=EASTER_WESTERN):
    """
    This method was ported from the work done by GM Arts,
    on top of the algorithm by Claus Tondering, which was
    based in part on the algorithm of Ouding (1940), as
    quoted in "Explanatory Supplement to the Astronomical
    Almanac", P.  Kenneth Seidelmann, editor.
    
    This algorithm implements three different easter
    calculation methods:
    
    1 - Original calculation in Julian calendar, valid in
        dates after 326 AD
    2 - Original method, with date converted to Gregorian
        calendar, valid in years 1583 to 4099
    3 - Revised method, in Gregorian calendar, valid in
        years 1583 to 4099 as well
    
    These methods are represented by the constants:
    
    * ``EASTER_JULIAN   = 1``
    * ``EASTER_ORTHODOX = 2``
    * ``EASTER_WESTERN  = 3``
    
    The default method is method 3.
    
    More about the algorithm may be found at:
    
    http://users.chariot.net.au/~gmarts/eastalg.htm
    
    and
    
    http://www.tondering.dk/claus/calendar.html
    
    """
    if not 1 <= method <= 3:
        raise ValueError("invalid method")
    y = year
    g = y % 19
    e = 0
    if method < 3:
        i = (19 * g + 15) % 30
        j = (y + y // 4 + i) % 7
        if method == 2:
            e = 10
            if y > 1600:
                e = e + y // 100 - 16 - (y // 100 - 16) // 4
    else:
        c = y // 100
        h = (c - c // 4 - (8 * c + 13) // 25 + 19 * g + 15) % 30
        i = h - h // 28 * (1 - h // 28 * (29 // (h + 1)) * ((21 - g) // 11))
        j = (y + y // 4 + i + 2 - c + c // 4) % 7
    p = i - j + e
    d = 1 + (p + 27 + (p + 6) // 40) % 31
    m = 3 + (p + 26) // 30
    return datetime.date(int(y), int(m), int(d))
